1. Field of the Invention
The present invention relates generally to Visible Light Communication (VLC), and more particularly, to a method and an apparatus for allocating multiple channels in a VLC system.
2. Description of the Related Art
Currently, research into visible light wireless communication using a visible Light Emitting Diode (LED) is being conducted by various companies and laboratories.
FIG. 1 illustrates a conventional VLC system.
Referring to FIG. 1, the VLC system includes a light source 10, which includes an LED or a Laser Diode (LD). The light source 10 transmits and receives data using visible light, while simultaneously functioning a light. The VLC system also includes a communication control device (not shown) for processing the data transmitted and received through the light source 10, and a VLC terminal 20, which includes a VLC transmitting/receiving module for transmitting/receiving data with the light source 10. The VLC terminal 20 may be a mobile terminal, such as a mobile phone or a PDA, or a fixed terminal, such as a desk-top computer. In addition, the VLC is combined with communication systems that use different wired/wireless communication media, so that it is possible to be more efficiently used.
Generally, when a VLC system is to provide service using the VLC in a wide space, multiple light sources are installed within the corresponding space, according to a service range of each light source.
FIGS. 2A to 2C illustrate service area conditions of two light sources 30 and 40.
Referring to FIGS. 2A to 2C, when the multiple light sources 30 and 40 are installed in predetermined intervals, a service area of each of the actual light sources can be represented in three cases.
Referring to FIG. 2A, the service areas of the light sources 30 and 40 overlap.
Referring to FIG. 2B, boundaries of the service areas of the light sources 30 and 40 are in contact with each other.
Referring to FIG. 2C, a non-service area is created between the service areas of the light sources 30 and 40.
Among FIGS. 2A to 2C, FIG. 2B is an ideal condition, but it is difficult to actually achieve this condition. Therefore, service areas according to multiple light sources generally include either an overlapped area in which the service areas are partially overlapped, as illustrated in FIG. 2A, or include a non-service area between the two service areas, as illustrated in FIG. 2C.
However, when the light source 30 and the light source 40 provide different kinds of services, data transmitted by the two services can collide with each other in a collision region, interfering with or even preventing the regular service. Further, normal VLC is not possible at all in the non-service area. As such, in order to provide the conventional VLC by the adjacent multiple light sources, there is a limitation in that the adjacent multiple light sources have to provide all of the users with the same service.